1. Field of the Invention
The present invention relates generally to the production and polarization of magnets and, more particularly, to the production and polarization of micro-sized, multi-pole magnets and magnets which have a multi-pole, micro-polarization pattern imposed thereon.
2. Brief Description of the Prior Art
Generally speaking, conventional permanent magnets are greater than one cubic centimeter in volume and have two or more magnetic poles on their surface which are greater than one millimeter in width. The fabrication of these magnets involves the formation of raw magnetic materials into a desired shape. The magnetic materials so shaped are then polarized to achieve the desired pole structure on the surface of the magnet. A variety of processes are known in the prior art for forming conventional magnets including injection molding, extrusion molding, cold pressing, and hot pressing, among others. Once the magnetic material is formed in the desired shape, the material is polarized in magnetization fixtures that consist of standard gauge wires imbedded in a support member that surrounds and/or encloses the formed magnet. The wires are threaded through the support member such that they are close to the surface of the enclosed magnet. To polarize the magnet, a high current (often in excess of 10,000 amps) is transmitted through the wires over a short time duration (typically on the order of one millisecond). The current pulse so transmitted through the wires produces an electromagnetic field which cuts across the magnet in such a way so as to impart the desired pole structure to the surface of the magnet.
While conventional technology is adequate for the production of conventional magnets, such technology is inadequate for the production of micro-sized magnets which will be generally referred to herein as "micromagnets". "Micromagnets" are magnets which are less than one cubic millimeter in total volume and which require surface poles as small as about 100 microns in width, or less. Conventional technology is also inadequate for the production of magnets greater than one cubic millimeter in total volume with micro-polarization patterns imposed thereon. Although it is possible using conventional methods to form conductors with cross-sections smaller than standard wire gauges, using such conventional methods in a process for forming micromagnets would be exceedingly expensive. Such conventional methods include electron discharge machining or chemically machining a solid conductor such as copper to obtain the desired conductive structure. Even though conductors such as bonding wire as used in the assembly of integrated circuits are available in diameters down to about 1.25 mils, conventional methods would make it impractical, if not impossible, to precisely thread such conductors through micro-sized molds for the production of magnets with micro-polarization patterns.